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"Noisey" ESC's?

R/C Submarine modelers

"Noisey" ESC's?

Postby Bob the Builder » Fri Apr 01, 2011 3:43 pm

I just ran into an issue with the refit of an Engel Akula that I'm working on. The previous ESC got shorted in chlorinated water and when I swapped it for a MTronics Marine 15 ESC, I had some crazy results.

When I engaged the drive motor, I got really bad glitching on all of the servos and ballast system (and speed controller channel). The faster I went, the worse the issue. I twisted the main power lead to the ESC thinking that I was getting some electrical interference from the main power lead to the speed controller, but the problem didn't seem to be affected one way or the other. For reference, the ESC is at the far aft end of the dry hull, and the receiver is in the forward center section. There is about 18" separating the main motor and ESC from the receiver.

I swapped out the Viper 15 this morning for a ModelController ESC and the problem is (almost) eliminated. There is still a very slight hint of it, but its very workable.

Are there more "dirty" speed controllers than others, and what can I do to eliminate the issue?
Bob Martin,
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Re: "Noisey" ESC's?

Postby mike stothers » Fri Apr 01, 2011 4:42 pm

Bob,look at the fifth item in the bulleted list http://www.microgyros.com/speed-control-setup.html

It is not that the first one was noisy.It is the modelcontrollers one has always had the same anti-glitch properties I incorporated from day 1.It was designed to cope with a poor radio response.
If my esc is not eliminating the glitching then I guess you must be using some dreadful drill motor I saw in your module.

Do you get a smell of electrical arcing from the motor? :lol:

You can do a lot more than a single 100nF capacitor across the motor.Got any CRT monitors or servers waiting to go to the scrapyard?
There are 500 size motors (555 from RS components in the UK) with ferrite suppression rings on the inside of the can.
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Re: "Noisey" ESC's?

Postby fgroza » Fri Apr 01, 2011 6:18 pm

There are glitch eliminators available from Rogue and shops in China like Hobbyking. Plugs into extra port, thats it.
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Re: "Noisey" ESC's?

Postby mike stothers » Sat Apr 02, 2011 11:59 am

Bob,I think it is worth you checking fgroza's suggestion just by temporarily using a receiver pack.
I have my doubts because I think it is plain old motor generated RF.The modelcontrollers ESC has a ground plane and the FETs are switched for minimal RF and it seems to improve things as it was intended.

I have several simple suggestions,some which depend on the battery voltage,others if you have the right components to hand.
The solution may be no more than earthing the motor case to the negative supply via a ground strap but I urge you do it via a ceramic capacitor and 22Ω resistor rather than a direct shorting link.It is just as effective and if you get a motor brush to to case fault you fry a 1cent resistor.

I actually gave(free issue) ferrite shield beads to some ESC customers who purchased for model subs.
The ones referred to in page 2 of the modelcontrollers ESC instruction leaflet for use with noisy motors.I think that is the best bet if a simple ceramic cap on the motor is not killing rf.

I didn't ever have cause to supply high value electrolytic caps to buffer the receiver supply.They are just the job for Mardave racers where motor and receiver are fed from the same 4 cell pack.
For your installation.....well how many servos do you use and what supply battery have you got?
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Re: "Noisey" ESC's?

Postby Sub culture » Sat Apr 02, 2011 4:22 pm

The Akula as supplied from Engel is a 6 volt boat. Also they usually use a separate receiver pack not a BEC.

Good to see you on here, Mike.
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Re: "Noisey" ESC's?

Postby Bob the Builder » Sun Apr 03, 2011 3:53 pm

This boat was modified to run on 7.2V NiMh battery packs. The Engel motor came set up with the proper capacitors installed. It was not, as was suggested, a "dreadful drill motor".

(and just as an aside, if you're referring to the motor that powered my scratchbuilt Nautilus, that motor was sourced from an automobile blower assembly. Its ultra high torque, low current draw, and has built in suppression direct from the factory (or else you'd have a helluva time listening to the radio with your heater working!))

The ModelController ESC has a built in BEC circuit which is driving the boat currently, however it was tried on a separate receiver pack with no noticeable reduction in glitching.

The current setup seems to be working well. There are a few momentary twitches every ten seconds or so, but its very liveable. Working on this sub is a royal pain in the butt, and I've sworn never to work on another dry hull boat of this size with those small access hatches.

On a positive note, the sub now seems to work in all functions perfectly. As a quick question, however, does (or did) Engel set up the TAE board so that if the boat lost radio signal it would not be able to cycle the ballast until after the power has been turned off and on? In my chlorinated swimming pool (aka "test tank"), I lost signal, the boat surfaced, and then I couldn't get it to dive again until after power was cycled off and then on again.

Except for that one quirk, everything seems to be working perfectly...
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Re: "Noisey" ESC's?

Postby mike stothers » Sun Apr 03, 2011 9:29 pm

I did indeed mistake the Nautilus motor for the DeWalt drill one.It kind of looks similar and you used the same RV sewer pipe as.....yeah him. :)

The same results with bec and the separate receiver pack,to me,seems to prove that putting a huge value electrolytic cap is not appropriate for the receiver.It can kill glitches in carpet racing buggies where a steering servo demands high current surges.It doesn't suppress motor generated r.f.

I can send a bunch of suppression components that I keep at arms reach.Those include ferrite beads with a 5mm hole and the right grade of ferrite material that takes fifty amp turns to reach saturation.That just means they work by threading it on the cable.No winding required.Without going to any trouble you can take the suppression of motors a lot further than that..I'll supply you with a goody bag for 10 subs or part list if you want.

You are saying that cycling the supply clears the fail safe?
The short answer is "check the battery is not a duffer !".

The long answer is it is maybe caused by a brown-out or momentary transient that triggers a low voltage failsafe?
That could be tested by a separate supply for TAE.
Is that not the Engel installation? I don't know.
Perhaps try a brand new, or higher capacity 7.2 or an 8.4 pack or 2s Lipo and perhaps cured by no more than a new battery.
Best of Luck!

Edit:
Is it Frank's old boat here on youtube? Part 1,Part 2
If so,the more I am thinking that the residual problem with the TAE might just be it activating a battery failsafe,just like you expect in brushless powered aircraft with long cables.Switches in the power lines are avoided there.
Stick a 2200μF capacitor onto the TAE supply right at its power terminals to see if that sorts it.

Does the TAE not flag up a low voltage fail safe or am I the only one that goes in for that?
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Re: "Noisey" ESC's?

Postby Sub culture » Mon Apr 04, 2011 4:57 am

I take it you isolated the BEC when trying the radio with a separate receiver pack?

Don't know much about Engel electronics- they appear to be microcontroller based relay switchers. Ramesh has a lot of experience with these boats, and Engel tend to supply pretty comprehensive instructions from what I've observed.

Andy
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Re: "Noisey" ESC's?

Postby Wheelerdealer » Mon Apr 04, 2011 10:03 am

With the Engel TAE board (at least the one I have), low voltage failsafe triggered requires requires you to switch the power off and on again to clear it, but loss of failsafe signal will clear once signal is restored.
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Re: "Noisey" ESC's?

Postby Larry Kuntz » Mon Apr 04, 2011 10:20 am

Just a quick thought. You say you swapped out the bad ESC for a Mtroniks ESC. Are you using a separate receiver battery pack? You must remember to remove the power wire from the plug on the ESC as this is trying to provide the power from the BEC to the receiver.
P.S. Sorry, I just noticed it in a previous post to isolate the BEC. That is what I described.
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Re: "Noisey" ESC's?

Postby Pirate » Mon Apr 04, 2011 11:22 pm

Bob,
I was getting the same problem with a Marine 25. I tried all the suggestions of noise reduction through capacitors and rings and such, and large grounding cables—none of it worked.

Don from Loyalhanna, from whom I bought the speed control, told me that he experienced the Mtronic products having a hard time running on the slot I was using in my receiver for the motor (I think it was 3—it's been a while now, and I didn't crack open my WTC to look, so I can't say which for sure, but it's the speed control slot.) You may try another slot and see if it clears up. Then, I guess you'd need to alter the levers on your radio if it fixes it.

Turned out not to be my problem. Mine was too much vibration from the motor on the WTC tray. When I separated the motor from touching the tray, problem (twitching) stopped. The Mtronic speed control was very sensitive to the vibration. So I used rubber bushings between the motor and the tray, and styrofoam where the WTC touched the WTC saddles in the hull, just like on the real boats where they separate the decks from the hull. This solved my problem.
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